Wrapping of baled polymers

ABSTRACT

Polymeric material such as solid particulate polymers as illustrated by butyl rubber, Vistanex, polyolefins such as polyethylene and polypropylene, and the like which contain residual moisture and/or gasiform material are baled and simultaneously encapsulated or wrapped in a baling zone, the interior wall of which is heated, and depending on the material being baled, subsequent to coating the wall with a polyolefin while applying mechanical pressure and reduced pressure to remove the moisture and/or gasiform material to form the bale.

United States Patent 1 Shelton et al.

[ 1March 13, 1973 1 'WRAPPING OF BALED POLYMERS [75] Inventors: MarcusH. Shelton, Baytown; Ralph James, Jr., Channelview, both of Tex.

[73] Assignee: Esso Research and Engineering Company, Linden, NJ.

[22] Filed: March 8,1971

[2]] Appl. No: 122,071

[52] US. Cl. ..264/l02, 264/112, 264/126, 264/300, 264/325 [51] Int. Cl..B29h 3/00, B29h 31/00 [58] Field of Search ..264/l01, 102, 125, 126,325, 264/112 [56] References Cited UNITED STATES PATENTS 3,526,688 91970 Shelton et al ..264/l02 3,048,537 8/1962 Pall ..264 '126 x SLU R RY DRYING Vogt ..264/l26 x Ranalli ..264/1 26 Primary Examiner-Robert F.White Assistant Examinen-Richard R. Kucia Att0rneyTh0mas B. McCulloch,Melvin F. Fincke, John S. Schneider, Sylvester W. Brock, Jr. and Chasonand Sinnock [57] ABSTRACT Polymeric material such as solid particulatepolymers as illustrated by butyl rubber, Vistanex, polyolefins such aspolyethylene and polypropylene, and the like which contain residualmoisture and/or gasiform material are baled and simultaneouslyencapsulated or wrapped in a baling zone, the interior wall of which isheated, and depending on the material being baled, subsequent to coatingthe wall with a polyolefin while applying mechanical pressure andreduced pressure to remove the moisture and/or gasiform material to formthe bale.

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SHEET my IN VENTORS.

MARCUS H- SHELTON, RALPH JAMES,JR.,

A T T OR N E Y.

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AT RNEY.

WRAPPING F BALE!) POLYMERS BACKGROUND OF THE INVENTION rubber,polyisobutylene, and the like, as well as solid polyolefins such as butnot limited to polyethylene, polypropylene, and the like. In its morespecific aspects, the invention is concerned with baling particulatepolymeric material while encapsulating the polymeric material as it isbaled.

2. Description of the Prior Art It is known to bale material andsynthetic rubber by subjecting a body of rubber particles or crumbs tomechanical pressure. It is also known to bale butyl rubber particles orcrumbs and the like by application of relatively high mechanicalpressure under certain conditions. It is also known that butyl rubberand the like may be baled by using relatively low pressures sinceapplication of the higher pressures was necessary to produce a balewhich could be shipped without deformation until it was discovered thatrelatively low pressures may be used as the confined body of theparticulate elastomer was subjected to reduced pressure which removesmoisture, volatiles, and occluded gases such as air. Once thesematerials, which are compressible, were removed they were not includedin the bale and on release of pressure the bale did not deform as itheretofore had, rupturing the bale and sometimes the container in whichthe bale was shipped.

In the prior art, after the bale was formed, it was common practice toencapsulate the bale in a film of a polyolefin such as polyethylenewhich heretofore was conducted in a separate step. It was also commonpractice to coat the bale with a powder such as zinc stearate and thelike to prevent sticking; however, the use of a film of polyolefin suchas polyethylene required a separate step and machinery to complete thewrapping operation before the bale was packaged for shipping.

In accordance with the present invention, unobvious results are obtainedby baling particulate polymeric material such as elastomers andpolyolefins by applying low mechanical pressure under reduced pressureto remove gases and the like while wrapping or encapsulating the baleduring its formation. The present invention, therefore, allows theobtaining of unobvious results.

The following listed U.S. patents were considered with reference to thisinvention:

U.S. Pat. No. 2,324,995 U.S. Pat. No. 3,023,513 U.S. Pat. No. 3,067,462U.S. Pat. No. 3,098,695 U.S. Pat. No. 3,264,387 U.S. Pat. No. 3,321,889U.S. Pat. No. 3,377,553 U.S. Pat. No. 3,461,641

SUMMARY OF THE INVENTION The present invention may be briefly describedand summarized as involving the baling of polymeric materialparticularly in a particulate form. The polymeric material may suitablybe butyl rubber particles or crumbs and the like containing occluded orentrained volatile and gasiform material such as moisture, hydrocarbons,hydrocarbon derivatives, air, gases and the like. The body of theparticulate material is subjected to a reduced pressure to remove thevolatile and gasiform material while applying mechanical pressure withinthe range from about 60 to about 300 pounds for a sufficient length oftime to form a compressed high density bale, a feature of the inventionbeing subjecting the outer edges of the body to heat while compressingthe body to form the bale. The wall of the baling zone in which the bodyis formed may be suitably coated with a polyolefin before introductionof the particulate material and the wall heated to a temperature abovethe melting point of the polyolefin such that as the bale is formed asit is encapsulated in the polyolefin.

VARIABLES OF THE INVENTION The inner wall of the baling zone may beheated to a temperature within the range of about 180 to about 350 F.usually to about 290F. to about 240F. to volatilize the solvent orsuspending fluid and to melt the polyolefin. If the bale is apolyolefin, the outer edges are heated sufficiently to melt same andform a film encapsulating the bale. Of course, the temperature of theinner wall may be adjusted to compensate for the boiling point of anyresidual solvent in the particulate material, but usually will be in therange given.

The polymeric material is suitably polyolefin such as solidpolyethylene, solid polypropylene, polyisobutylene known to the trade asVistanex, butyl rubber, and the like.

The mechanical pressure applied for polyolefin powder may range fromabout 50 to about 500 psig. For polyolefin pellets, the mechanicalpressure may be from about to about 1000 psig while for butyl rubber themechanical pressure may range from about 50 to about 250.

The mechanical pressure may be applied or held (dwell time) from about 5to about 30 seconds. For butyl rubber the dwell time may range fromabout 3 to about 20 seconds while for polyolefins it may range fromabout 3 to about 20 seconds.

The reduced pressure may be within the range of from about 0.5 to 29inches Hg. A suitable pressure may be from about 3 to about 20 inchesHg. for butyl rubber and from about 0.5 to about 29 inches forpolyolefin.

The baling of particulate polymers and/or elastomers is accomplished, asdescribed, provided that baling pressure, top to bottom, is sufficientto distort the baler charge significantly in the top to bottom dimensionand bond the particles partially together. When this top to bottompressure is released, the subsequent elastic response in the'baledparticles causes the bale to increase in height and to decrease inhorizontal dimension by a similar amount. This horizontal shrinkageallows the bale to detach itself from the cavity walls withoutsubstantial distortion of the fused coating and/or the bale. Theapplication of known release promoting compounds is indicated to furtheraid in this process of releasing the bale from the cavity part. Therequired degree of vacuum is inversely related to the elasticity of thematerial to be baled.

BRIEF DESCRIPTION OF THE DRAWING The present invention will be furtherdescribed and illustrated by reference to the drawing in which:

FIG. 1 is a flow diagram of a preferred mode of conducting theinvention;

FIG. 2 is an isometric view of one type of baler such as is employed inFIG. 1; and

FIG. 3 is a sectional view of a baling zone with provision for coatingthe interior wall of the baling zone and for heating the wall.

DESCRIPTION OF THE PREFERRED MODE AND EMBODIMENTS WITH RESPECT TO THEDRAWING Referring now to the drawing and particularly to FIG. 1, numeral11 designates a discharge line from the slurry tanks of a butyl rubberoperation by way of which the aqueous slurry of butyl rubber isintroduced into filtering means such as Oliver type filters 12. In thefilter 12, the aqueous fluid is substantially removed and discharged byline 13, while the filtered butyl rubber particles or crumbs areintroduced into a screw conveyor 14 whereby the filtered crumbs areintroduced into a drying system such as a drying train 15 provided withsuitable heating facilities to raise the temperature of the crumbs to atemperature in the range from about 100F. to about 300F. sufficient toremove substantially all of the water from the crumbs or butyl rubberparticles. For example, the crumbs or particles in conveyor 14 may havea water content ranging from about 20 to about 30 percent by weight;whereas, in the drying train 15 the water content is reduced to about0.001 to about 5.0 percent by weight. A portion of the drying train 15is suitably provided with means for cooling the heated crumbs, orsuitably a section such as 16 of the drying train 15 may omit theheating facilities such that the temperature of the dried butyl rubberparticles or crumbs may be controlled. From the section 16 of the dryingtrain 15, the dried particles or butyl rubber crumbs are discharged at atemperature within the range from about 160 to about 180F. andintroduced by a screw conveyor 17 via a feeder 17A onto scales 18 wherethe crumbs are suitably weighed prior to discharging by hopper means 19into a baler 20, which is described in more detail with respect to FIG.2. The baler 20 is provided with a hydraulic mechanism, including apiston and cylinder 21, operated by a suitable source of hydraulic fluid22. The bales of butyl rubber are discharged from the baler 20 onto aconveyor 23 from whence the bales are discharged.

Referring now to FIG. 2, the baler, generally indicated by numeral 20,in comprised of a rectangular shape member 25 defining a cavity 26 intowhich the particles of butyl rubber are discharged from the hopper means19. The piston and cylinder arrangement 21 is provided with hydraulicfluid lines 27 and 27a for introduction and withdrawal of hydraulicfluid. The hydraulic mechanism 21 carries a ram 28 which actuates ablock 29 having a size and shape such that it is movable verticallywithin the cavity 26. The upper end of the baler 20 is closed by asuitable block 30 which is movable laterally by a moving mechanism 31which also may be hydraulically operated. As the butyl rubber particlesare introduced into the top of the cavity 26,

the block 30 is moved laterally to close the top of the cavity, and thenpressure is exerted by the hydraulic mechanism to raise the block 29into the cavity 26 to apply mechanical pressure thereto to form thebales under the temperature and pressure conditions and time of contactor dwell time given. Under these conditions, a bale having a densitysuitable for shipment is formed. The block 30 is withdrawn laterally andthe block 29 is raised to discharge the bale out of the upper end. Theblock 30 then is again moved laterally to shove the bale onto theconveyor 23.

It is to be understood that the baler 20 of FIGS. 1 and 2 may besuitably equipped with means for spraying the inner surface thereofincluding the block 29 and block 30. Furthermore, it will be understoodthat the baler 20 includes provisions for heating the inner surface ofthe outer periphery of cavity 26 and also for reducing pressure in thecavity 36.

Referring now to FIG. 3 in which a sectional view of a baling zone 40 isshown, the baling zone 40 is provided with a heating jacket 41 intowhich 'a conduit 42 controlled by valve 43 leads via which a heatingfluid may be introduced. A conduit 44 controlled by valve 45 providesfor circulation of the heating fluid. The heating fluid is introducedthrough line 42 and circulates through the jacket 41 and out throughline 44. The heating fluid is at a sufficient temperature to raise theinternal wall of cavity 46 to a temperature within the range of about200 to about 350F., if the baled material is to be merely fused, as inbaling polyolefins. If the bale is to be an elastomer wrapped in apolyolefin jacket, the wall temperature is above the melt point of thepolyolefin.

The baling zone 40 has a top cover 47 which is hingedly connected bypivot 48 to the zone 40 and latched thereto by latch 49 provided with aseal 50. The top cover 47 has a conduit 51 controlled by valve 52 forreducing the pressure in the cavity 46 and thereby removing occludedand/or entrained gasiform material from the cavity 46 and theparticulate polymeric material.

The cover 47 is hingedly connected by a counter weight means 53including a counter weight 54 and an arm 55 connected to upstandingmember 46. The arm 55 is pivotally connected by pin 57 to a bracketmember 58 which is connected by member 59 to the baling zone 40.

Arranged in the cavity 46 is a block or piston member 60 provided with asealing means 61 which seals with the inner wall of baling zone 40, theblock or piston 60 being connected to a member 62 which is arranged instuffing box means 63 for movement in a vertical direction as airpressure is introduced into the cavity 46 below the piston 60 by conduit64 controlled by valve 65. Pressure is released from the cavity 46 byconduit 66 controlled by valve 67 which allows the piston or block 60 tomove downwardly. The block or piston 60 is provided with a hinged valve68 designed to seat on a seat 69 on the block or piston 60 and seal withseal 70.

When it is desired to coat the interior wall of zone 40 an elongatedmember 71 connected by flexible pressure hose 72 to a conduit 73controlled by valve 74 is raised through valve 68 by pressure appliedthrough conduit 75 controlled by valve 76 against piston 77 attached toan elongated perforated member 78. Pressure is released from the cavity79 below the piston 77 by conduit 80 controlled by valve 81.

The upper end of the elongated member 78 is provided with numerousperforations or nozzles designated as 82 through which a spray or jetsof a polyolefin suspension or solution may be sprayed against thesurface of the cavity $6. The solution or suspension may also contain asuitable powder such as to prevent sticking if there is any tendency ofsuch. Thus, the inner surface of the cover 47, the walls of the balingzone 40 and the upper surface of the block or piston 60 may be suitablysprayed with a polyolefin suspension. For example, the spray maycomprise polyethylene powder, polyethylene powder and talc, or tale, ina solvent containing silicone oils, and the like.

The operation of the present invention, particularly with respect toFIG. 3 is as follows:

It is assumed that the cavity 46 has been freed of a bale of solidpolymeric material as shown in FIGS. 1 and 2. When this happens, thecover 47 is swung back into place and latched and sealed to form apressure tight cavity 46. The spray head 82 is raised by introduction ofpressure under the piston 77 and polyolefin suspension is then fedthrough the conduit 73, the hose 72, and the elongated member 71 intothe cavity 46 to thoroughly coat the exposed surfaces of the cavity 46.

Pressure is then released by opening valve 81 which allows the member 78to drop downwardly allowing valve 68 which is spring loaded to close andseat and seal on the seat 69. The cover 47 is then opened and a load ofthe particulate polymeric material is dropped into the cavity 46 on tothe block or piston 60 in its lowered position as illustrated.

As fluid pressure, such as air and the like is introduced by conduit 64,heating fluid is circulated through the jacket 41 causing the inner wallof cavity 46 to be heated; sufficient heat also being transmitted to theinner surface of cover 47 and the upper surface of piston 60. Asufficient amount of heat is applied to raise the outer periphery ofcavity 46 to a temperature above the melting point of the polyolefinintroduced by spray head 82 and to melt same. At the same time reducedpressure is being applied through the conduit 51 by opening valve 52 toremove gasiform materials while the piston 60 is being raised byintroduction of fluid pressure such as air and the like to providesufficient mechanical pressure to form the bale. The temperature of theperiphery of cavity 46 is sufficient to volatilize the carrier orsolvent for the suspension or solution which may be methyl chloride whenbutyl rubber is being baled and iso and normal paraffins,cycloparaffins, naphthenes, aromatics and the like boiling from about100 to about 750F. when polyolefins are being baled. Ordinarily the highboiling solvents will not be used but solvents will be used boilingwithin the range given and volatilizable at the reduced pressure and atthe temperature of the baler, and to melt the polyolefin to wrap orencapsulate the bale as it is being formed such that when the bale isejected as shown in FIGS. 1 and 2 it is already wrapped and ready forpackaging.

Thus, the present invention allows the obtaining of unobvious results informing a bale and encapsulating or wrapping it in one operationentirely eliminating expensive and time consuming steps and equipment.Thus, the present invention is quite unobvious and useful.

The butyl rubber which is baled in accordance with the present inventionis manufactured by techniques well known in the art. Briefly, butylrubber is a copolymer of diolefin and a tertiary mono-olefin. Forexample, isoprene or butadiene and isobutylene are reacted at atemperature in the range from about 40 F. to about -l60F. in thepresence of a Friedel-Crafts catalyst such as aluminum chloride. Thecatalyst system is ordinarily aluminum chloride in methyl chloride andthe mixture of isoprene and isobutylene, for example, contacts thecatalytic solution in a tubular type of reactor at low temperatureconditions to form a slurry of butyl rubber particles in solution in adiluent which may also be methyl chloride. The slurry is then introducedinto water to form a slurry of butyl rubber, generally in the form ofcrumbs, in the water. The water is then removed from the slurry and thecrumbs or particles of butyl rubber are recovered in accordance with thepresent invention. A description of a method for producing butyl rubbermay be found in U.S. Pat. No. 2,474,592.

The polyolefin employed in the present invention may be produced bycontacting an olefin such as polypropylene with a catalyst such as TiCl.l/3 aluminum chloride at a temperature within the range of about 32F.to about 350F. The manufacture of polypropylene is well known and isdescribed in U.S. Pat. No. 3,032,510.

The Polyethylene employed in the present invention may be either lowdensity polyethylene produced by high pressure polymerization ofethylene in the presence of oxygen yielding catalyst or high densitypolyethylene which may be produced by contact with a catalyst such as aZiegler catalyst at a temperature of about 32 to about 250F. such asdescribed in the Ziegler patents. Both low and high density polyethylenemay be baled in accordance with the present invention. High densitypolyethylene may be produced similarly to the production ofpolypropylene.

While the present invention has been described and illustrated withrespect to specific equipment and materials, it is understood that it isapplicable to other polymeric material which is susceptible to balingand which is wrapped in a film which may be melted.

The nature and objects of the present invention having been completelydescribed and illustrated and the best mode contemplated set forth whatwe wish to claim as new and useful and secure by Letters Patent is:

l. A method of encapsulating compressible solid elastomeric materialwhich comprises:

applying a coating of polyolefin to the interior wall of a baling zone;

forming a body of said solid material in said baling zone; and

in one operation applying mechanical pressure within the range of 60 to300 psig to said body for a time from about 3 to about 30 seconds underreduced pressure within the range of 0.5 to 29 inches I-llg absolute insaid zone while applying heat only to the outer edges of said bodysufficient to raise the temperature of said polyolefin above its meltingpoint and form a film of said polyolefin encapsulating said body as saidbody is reduced in volume and increased in density. 2. A method inaccordance with claim 1 in'which the solid elastomeric material is butylrubber.

3. A method in accordance with claim 1 in which the solid elastomericmaterial is particulate.

4. A method in accordance with claim 1 in which the polyolefin powdercomprises polyethylene powder.

5. A method in accordance with claim 1 in which the polyolefin powdercomprises polypropylene powder.

6. A method in accordance with claim 1 in which the elastomeric materialis polyisobutylene.

7. A method in accordance with claim 1 in which the

1. A method of encapsulating compressible solid elastomeric materialwhich comprises: applying a coating of polyolefin to the interior wallof a baling zone; forming a body of said solid material in said balingzone; and in one operation applying mechanical pressure within the rangeof 60 to 300 psig to said body for a time from about 3 to about 30seconds under reduced pressure within the range of 0.5 to 29 inches Hgabsolute in said zone while applying heat only to the outer edges ofsaid body sufficient to raise the temperature of said polyolefin aboveits melting point and form a film of said polyolefin encapsulating saidbody as said body is reduced in volume and increased in density.
 2. Amethod in accordance with claim 1 in which the solid elastomericmaterial is butyl rubber.
 3. A method in accordance with claim 1 inwhich the solid elastomeric material is particulate.
 4. A method inaccordance with claim 1 in which the polyolefin powder comprisespolyethylene powder.
 5. A method in accordance with claim 1 in which thepolyolefin powder comprises polypropylene powder.
 6. A method inaccordance with claim 1 in which the elastomeric material ispolyisobutylene.
 7. A method in accordance with claim 1 in which thepolyolefin is a suspension.
 8. A method in accordance with claim 1 inwhich the interior wall of the baling zone is coated with a suspensionof polyethylene powder and talc.
 9. A method in accordance with claim 1in which the interior wall of the baling zone is coated with apolyethylene solution containing talc and silicone oil.
 10. A method inaccordance with claim 1 in which the elastomer is an olefinic copolymer.